For digital signal processing devices such as display devices inputting a digital signal via a digital signal cable such as a High-Definition Multimedia Interface (HDMI) terminal or a Digital Visual Interface (DVI) terminal it may be difficult to determine whether or not an electronic apparatus for outputting a digital signal is connected to the digital signal cable because of the standard of the digital signal cable (see, for example, Japanese Patent Publication No. JP-A-2007-36854).
In such digital signal processing devices, a method of determining whether or not the electronic apparatus is connected based on a presence or absence of a Transition Minimized Differential Signaling (TMDS) signal has been adopted.
However, since some of the electronic apparatuses output the TMDS signal after a High-bandwidth Digital Content Protection (HDCP) certification has finished, it may take time before the TMDS signal is input to the digital signal processing device, and therefore, it may also take time before it is determined that the TMDS signal will not be input.
For example, if a digital signal cable for coupling an electronic apparatus and a digital signal processing device is detached therefrom, it takes about five seconds for a typical digital signal processing device before notifying the user of the no signal state. This may contribute to a poor user experience or make the user feel anxious.